Before floating groups copies could float or not. If they floated then they floated everywhere, with no restrictions.

After floating groups where a copy will float is defined by what group it has been assigned to.

Floating Groups

Each floating group comes with a name and a manual flag, plus zero or more group members. The name is used solely for selection and display purposes.

The manual flag dictates whether or not the "Manual Floating Active" checkin modifier needs to be active for a copy to float. This allows for greater control over when items float. It also prevents automated checkins via SIP2 from triggering floats.